Interactive display devices are known, which can undergo a change in optical appearance in response to some form of external stimulus. Typically, such devices comprise a layered or multi-layered structure where user manipulation of the device, or a user-initiated external influence upon the device, causes a change in appearance of the device, or at least a portion thereof.
However, there remains a need in the art for variable devices, optionally in the form of a display screens or thin-layer devices, that can undergo some form of observable or detectable optical or physical change when under an external influence. The need extends to display devices with relatively simple or more complex content, that are single use or that can repeatedly undergo the same change in optical or physical characteristics. Ideally, though not necessarily, there is a need for such devices that can be manufactured in a relatively simple and inexpensive manner. The need for such devices extends into multiple disciplines, including but not limited to interactive media material, advertisements, magazines, books or other paper items with user-manipulated content, advertizing billboards, and authentication devices for security documents such as passports, credit cards and bank notes to help prevent counterfeit.
In particular, there is a need for such devices that are typically flat or planar in nature so that optionally they can take the appearance of being flush with a planar substrate to which they are applied, even including (but not limited to) devices that are amenable to folding, bending or crumpling without significant damage or affect upon the functionality of the device, thus to improve robustness and longevity of the device when located within or mounted upon a rigid or non-rigid substrate.